* as a simple wildcard works in search within results, but it's kind of a machete, and it sometimes does things with logic I can't figure out, so use with caution. Filtering out *reader* should take out all readerfic, but it will also filter out, say, anyone addressing Dear Reader in their summary. It doesn't work on the "other tags" boxes, afaict.

Also, "search within results" treats / as the end of a word, so for that specific case, putting "reader" without the * in works almost as well.